Linear dispersion of non-newtonian fluid

Non-Newtonian fluids have different rheological properties under stress. According to the changes in their rheological properties, they can be divided into three types of curves: shear stress-shear rate curves, also known as rheological curves. The following are the differences between the three types of curves for non-Newtonian fluids:

Plastic Fluid:

Plastic fluids behave as solids at low shear rates and require a certain shear stress (critical shear stress) to begin flowing. When the shear stress exceeds the critical value, there is a linear relationship between the shear rate and the shear stress.

When the shear stress is below the critical value, the plastic fluid behaves as a rigid solid and has no fluidity. Only when the shear stress exceeds the critical value can plastic deformation occur and flow begin.

The rheological curve of plastic fluid presents two obvious stages: one is that the shear stress remains basically unchanged, and the other is that there is a linear relationship between the shear stress and the shear rate.

Examples of plastic fluids include some greases, plastic pastes, and the like.

Pseudo Plastic Fluid: 

Pseudoplastic fluids exhibit high viscosity at low shear rates, but their viscosity gradually decreases with increasing shear rates. In pseudoplastic fluids, there is a nonlinear relationship between shear stress and shear rate, and an increase in shear stress leads to an increase in shear rate.

The rheological curve of pseudoplastic fluid shows a decreasing trend, its slope is getting smaller and smaller, and the relationship between shear stress and shear rate is not linear.

Examples of pseudoplastic fluids include some colloidal solutions, coatings, certain food pastes, and the like.

Dilatant Fluid: 

True plastic fluids exhibit low viscosity at low shear rates, but their viscosity gradually increases with increasing shear rates. In true plastic fluids, there is a nonlinear relationship between shear stress and shear rate, and the increase of shear stress leads to a decrease in shear rate.

The rheological curve of the true plastic fluid shows a gradually increasing trend, and its slope is getting larger and larger, and the relationship between shear stress and shear rate is not linear.

Examples of true plastic fluids include concrete, particle suspensions, and the like.

Different non-Newtonian fluids may have different rheological properties and characteristics. The above description is a general generalization. In specific applications, it is also necessary to analyze and judge according to the rheological properties of actual materials and experimental data.